The invention relates to a novel group of 3-tetrahydropyridin-4-yl indole derivatives of the formula (I):
- R1 is halogen, CF3, alkyl (1-3C), alkoxy (1-3C), CN or SCH3
- m the value 0, or 2
- R2 is H or alkyl (1-3C)
- n has the value 3,4,5 or 6
- R3 is halogen, alkyl (1-4C) or alkoxy (1-4C)
- p has the value 0,1, or 2
It has been found that the compounds having formula (I) show high affinity for the dopamine D2-receptor and are good serotonin reuptake inhibitors (SRI's).
Preferred compounds of the invention are compounds having formula (I) wherein R1 hydrogen (i.e. m=0) or F, Cl, CH3 or CN, and m=1, R2 is H or CH3, n=4, R3 is hydrogen (i.e. p=0), or F or alkyl (1-4C), p=1, and the salts thereof.
Especially preferred is the compound having formula (I)
wherein (R1)m is F, R2 is hydrogen, n=4 and p=0, and the salts thereof.
It has been found that the compounds according to the invention show high affinity for both the dopamine D2 receptor and the serotonin reuptake site. This combination is useful for the treatment of schizophrenia and other psychotic disorders and might allow for a more complete treatment of all disease symptoms (e.g. positive symptoms and negative symptoms).
The compounds show activity as antagonists at dopamine D2 receptors as they potentially antagonize apomorphine-induced climbing behaviour in mice. The compounds also show activity as inhibitors of serotonin reuptake, as they potentiate 5-HTP induced behaviour in mice.
The compounds are active in therapeutic models sensitive to clinically relevant antipsychotics (e.g. the conditioned avoidance response; Van der Heyden & Bradford, Behav. Brain Res., 1988, 31:61-67) and antidepressants or anxiolytics (e.g. suppression of stress-induced vocalization; van der Poel et al., Psychopharmacology, 1989, 97: 147-148).
In contrast to clinically relevant dopamine D2 receptor antagonists the described compounds have a low propensity to induce catalepsy in rodents and as such are likely to induce less extrapyramidal side effects than existing antipsychotic agents.
The inhibitory activity of serotonin reuptake inherent in these compounds may be responsible for the therapeutic effects observed in behavioural models sensitive to either antidepressants or anxiolytics.
The compounds can be used for the treatment of affections or diseases of the central nervous system caused by disturbances in either the dopaminergic or serotonergic systems, for example: aggression, anxiety disorders, autism, vertigo, depression, disturbances of cognition or memory and in particular schizophrenia and other psychotic disorders.
Pharmacologically acceptable acids with which the compounds of the invention can form suitable acid addition salts are for example hydrochloric acid, sulphuric acid, phosphoric acid, nitric acid, and organic acids such as citric acid, fumaric acid, maleic acid, tartaric acid, acetic acid, benzoic acid, p-toluene sulphonic acid, methanesulphonic acid and naphthalene sulphonic acid.
The compounds are their acid addition salts can be brought into forms suitable for administration by means of suitable processes using auxiliary substances such as liquid and solid carrier materials.
The compounds having formula (I) can be obtained as follows:
- by reaction of a compound of formula (II)
- with a compound of the formula (III)
This reaction is carried out in a solvent such as acetonitrile in the presence of triethylamine or K2CO3 and Kl at reflux temperature, or
- a) by
- (i) reduction of the cyano group in a compound of formula (IV)
- (ii) reacting the obtained amine with an optionally substituted phthalic anhydride of the formula (V)
- (i) reduction of the cyano group in a compound of formula (IV)
Reaction step b (i) can be carried out for example with LiAlH4 in an organic solvent such as tetrahydrofuran at reflux temperature.
Reaction step (ii) can be carried out for example in organic solvents such as tetrahydrofuran and toluene at reflux temperature.
The starting compounds as used in method a) of the formula (II) can be obtained in a manner known per se by reaching an optionally substituted indole derivate with 4-piperidone.
The starting compounds used in method b) having formula (IV) can be obtained by reaction of a compound having formula (II) with a bromoalkyl nitrile of the formula Br-(CH2)n-1-CN in a manner known per se.
The preparation of the compounds having formula (I) will now be described in more detail in the following Examples.
Preparation of 1-methyl-3-(1,2,3,6-tetrahydropyridin-4-yl)indole.
To a solution of 4-piperidone.H2O.HCl (50 g, 0.32 mol) in 100 ml of acetic add and 150 ml of trifluoroacetic acid was added dropwise a solution of 1-methylindole (11.5 ml, 0.09 mol) in 100 ml of acetic add at room temperature. After stirring for 1h the reaction mixture was concentrated (in vacuum, temp. ca. 30°C), water was added, the mixture was made basic with potassium carbonate and extracted with ethyl acetate. The organic layer was separated, dried and purified by silica gel column chromatography (dichloromethane/methanol/ammonium hydroxide = 84/15/1) to give
9 g (47%) of the title compound.
Preparation of 5-fluoro-3-(1,2,3,6-tetrahydropyridin4-yl)indole.
To a solution of sodium (60 g , 2.6 mol) in 1000 ml of methanol was added 5-fluoroindole (49 g, 0.36 mol) and 4-piperidone.H2O.HCl (170 g, 1.11 mol). The mixture was heated under reflux for 18h, then concentrated, water was added and extracted with ethyl acetate. The combined organic layer was dried over sodium sulfate and then concentrated. The resulting solid was dissolved in methanol (about 200 ml) and then diluted with water (about 1000-1500 ml). The precipitate was collected, washed with water and petroleum ether and then dried in a vacuum oven at 60°C. Yield 74 g (95%) of a yellow solid.
A solution of 5-fluoro-3-(1,2,3,6-tetrahydropyridin-4-yl)indole (7.5 g, 34.7 mmol), N-(4-bromobutyl)phthalimide (10.8 g, 38.3 mmol), triethylamine (4.5 ml) and potassium iodide (5.5 g) in 150 ml of acetonitrife was heated under reflux for 18h. The reaction mixture was concentrated and purified by silica gel column chromatografy (dichloromethane/methanol /ammonium hydroxide= 92/7.5/0.5) to give 8.3 g of the title compound as a free base. Mp. 186°C. The hydrochloride was prepared by dissolving the above mentioned free base in 20 ml of 1 M HCl in ethanol. The solution was concentrated and the resulting solid was washed with ether. Yield 8.4 g (54%) of compound 1, mp. 224°C (dec.).
A solution of 5-fluoro-3-(1,2,3,6-tetrahydropyridin-4-yl)indole (10 g, 46 mmol), 4-bromobutyronitrile (5.6 ml, 56 mmol), potassium carbonate (6.3 g) and potassium iodide (7.6 g) in 100 ml of acetonitrile was heated under reflux for 18h. The mixture was filtered and the residue on the filter was washed with dichloromethane/methanol/ammonium hydroxide = 84/15/1. The organic layer was concentrated to give 10.9 g (83%) of the title compound. M.p 152°C.
To a solution of 5-fluoro-3-[1-(3-cyanopropyl)-1,2,3,6-tetrahydropyridin-4-yl]indole (10 g, 35 mmol) in 300 ml of dry THF was added slowly LiAlH4 (2.0 g). The mixture was stirred and heated to reflux for 2h. Then the reaction mixture was cooled and water (1.9 ml) in THF (10 ml) was added slowly, followed by 2N sodium hydroxide (1.9 ml). This mixture was heated to reflux for 0.25h, filtered over hyflo and concentrated to give 8.76 g (88%) of the title compound.
To a solution of 5-fluoro-3-[1-(4-aminobutyl)-1,2,3,6-tetrahydropyridin-4-yl]indole (1.46 g, 5 mmol) in 20 ml of THF was added 4-fluorophthalic anhydride and 50 ml of toluene. The THF was removed by distillation and the resulting mixture was heated to reflux for 18h, with azeotropic removal of water (Dean and Stark apparatus). The reaction mixture was concentrated and purified by silica gel column chromatografy (dichloromethane/methanol/ammonium hydroxide =92/7.5/0.5) to give 1.52 g (69%) of the title compound 19. M.p. 197-199°C.
According to method a) as illustrated in Examples 1-3, or method b) as illustrated in Examples 4-6 the compounds listed in the following Table have been prepared: